This invention relates generally to thermal solution attachment mechanisms, and in particular, the present invention relates to a reusable thermal solution attachment mechanism and methods of using same.
During manufacturing of microprocessors, a basic system or circuit board function test is typically performed prior to system assembly. As testing proceeds, the central processing unit (CPU or processor) heats up, thus requiring temporary processor cooling. Such cooling, even for a limited time, is critical to successful operation of the processor. Natural convection provided by the open air environment of the manufacturing setting aids in cooling, but additional cooling means are usually needed. Most often, a thermal solution is also used to cool the CPU by reducing thermal resistance between the thermal solution and the surface of the die, i.e., the unpackaged processor. Thermal solutions are also designed to provide mechanical pressure on the processor, in order to improve thermal performance.
In the mobile environment, most manufacturers secure temporary thermal solutions to the die surface with thermal tape or adhesives. In mobile processors that require only 15 to 18 watts of power to be drawn off near a temperature of about 100xc2x0 C., such methods have been relatively successful in keeping the processor adequately cooled. However, thermal tape and adhesives are often not reusable and can leave residual material on the die surface.
Another method involves placing the thermal solution on top of the package, allowing the weight of the components to provide the requisite pressure to the processor contained within. However, the applied pressure with this method is not always consistent and is oftentimes inadequate.
Temporary fasteners are also not a practical option in most instances as they are difficult to attach and remove quickly during manufacturing, particularly with the smaller components used in mobile applications. Additionally, clips or fasteners that attach directly to a CPU package rather than to the circuit board, can easily damage or pinch the processor. Such a configuration may also pull the processor away from the circuit board surface, possibly hampering the integrity of the solder joint between the package and circuit board. For socket mounted packages, the use of such clips may also require redesign of the socket itself.
As processing power increases, heat generated by the processor increases. Recently developed mobile applications use processors requiring 30 watts or more of power to be drawn off near a temperature of about 100xc2x0 C. None of the currently known methods of applying thermal solutions are able to provide the requisite pressure on the processor, even during relatively brief periods of operation. Such inconsistent or inadequate pressure can, in turn, lead to excessive thermal resistance between the die and thermal solution, thus reducing the ability of the thermal solution to keep the components sufficiently cool. Without adequate cooling means, a processor can exceed the junction temperature specification, causing the processor operation to halt during testing, thus compromising future reliability of the processor.
For the reasons stated above, there is a need in the art for a simple, yet effective means for cooling high power processors.